As is known, sensing elements are used in a variety of applications to sense characteristics of an environment. Sensing elements include, but are not limited to, pressure sensing elements, temperature sensing elements, light sensing elements, acoustic sensing elements, and magnetic field sensing elements.
A magnetic field sensor can include one or more magnetic field sensing elements and also other electronics.
Magnetic field sensors can be used in a variety of applications. In one application, a magnetic field sensor can be used to detect a direction of a magnetic field. In another application, a magnetic field sensor can be used to sense an electrical current. One type of current sensor uses a Hall effect magnetic field sensing element in proximity to a current-carrying conductor.
Planar Hall elements and vertical Hall elements are known types of magnetic field sensing elements that can be used in magnetic field sensors. A planar Hall element tends to be responsive to magnetic field perpendicular to a surface of a substrate on which the planar Hall element is formed. A vertical Hall element tends to be responsive to magnetic field parallel to a surface of a substrate on which the vertical Hall element is formed.
Other types of magnetic field sensing elements are known. For example, a so-called “circular vertical Hall” (CVH) sensing element, which includes a plurality of vertical magnetic field sensing elements, is known and described in PCT Patent Application No. PCT/EP2008/056517, entitled “Magnetic Field Sensor for Measuring Direction of a Magnetic Field in a Plane,” filed May 28, 2008, and published in the English language as PCT Publication No. WO 2008/145662, which application and publication thereof are incorporated by reference herein in their entirety. The CVH sensing element is a circular arrangement of vertical Hall elements arranged over a common circular implant region in a substrate. The CVH sensing element can be used to sense a direction (and optionally a strength) of a magnetic field in a plane of the substrate.
Conventionally, all of the output signals from the plurality of vertical Hall elements within the CVH sensing element are needed in order to determine a direction of a magnetic field. Also conventionally, output signals from the vertical Hall elements of a CVH sensing element are generated sequentially, resulting in a substantial amount of time necessary to generate all of the output signals from the CVH sensing element. Thus, determination of the direction of the magnetic field can take a substantial amount of time.
Various parameters characterize the performance of sensing elements (and sensors that use sensing elements) in general, and magnetic field sensing elements (and magnetic field sensors) in particular. Taking a magnetic field sensing element as an example, these parameters include sensitivity, which is a change in an output signal of a magnetic field sensing element in response to a change of magnetic field experienced by the magnetic sensing element, and linearity, which is a degree to which the output signal of the magnetic field sensing element varies in direct proportion to the magnetic field. These parameters also include an offset, which is characterized by an output signal from the magnetic field sensing element not representative of a zero magnetic field when the magnetic field sensing element experiences a zero magnetic field. Other types of sensing elements can also have an offset of a respective output signal that is not representative of a zero sensed characteristic when the sensing element experiences the zero sensed characteristic.
Another parameter that can characterize the performance of a sensor (e.g., magnetic field sensor) is the speed with which output signals from associated sensing elements (e.g., magnetic field sensing elements) can be sampled.
Magnetic field sensors can be used to identify a direction of a magnetic field. For example, in one application, a magnetic field sensor can be used to identify a rotation speed of a target object upon which a magnet is disposed. The magnetic field sensor may have a limit as to how rapidly the magnetic field sensor can identify the direction of the magnetic field, and thus, may have a limit as to how rapidly the target object can rotate and be properly sensed by the magnetic field sensor. Particularly for magnetic field sensors that use a plurality of magnetic field sensing elements (e.g., a CVH sensing element), which are scanned sequentially, the limitation of the magnetic field sensor may be unacceptable.
Thus, it would be desirable to provide a magnetic field sensor that can more rapidly identify a direction of a magnetic field. More generally, it would be desirable to provide a circuit that can more rapidly identify an angle of a direction of a sensed parameter sensed by a plurality of measuring devices.